Medical electronic instruments are often highly sophisticated, complex systems that include a large number of electronic circuits and other components, such as displays, printers, keyboards, etc. Instruments of this nature are inherently prone to damage if the instruments are exposed to such environmental hazards as rain, snow, accumulated water, and shock.
Most medical electronic instruments are normally used in the controlled environment of a hospital, doctor's office, or the like. Such instruments are therefore generally not exposed to such environmental hazards as rain, snow, or accumulated moisture. Furthermore, they are generally either stationary or carried on a cart or other vehicle during transport so that they are not subject to shock, such as by being dropped onto a floor. However, some medical electronic instruments, by their very nature, must be used outdoors where they can readily be exposed to a variety of environmental hazards. Furthermore, some of these instruments are often used in emergency conditions where medical personnel cannot devote attention to protecting the instrument from these environmental hazards.
One type of medical electronic instrument that may be exposed to environmental hazards under emergency conditions is the portable defibrillator. For many years portable defibrillators have been supplied to emergency medical technicians who are called upon to respond to heart attack victims in a wide variety of settings. Modem portable defibrillators do far more than applying a controlled shock to heart attack victims in order to arrest fibrillation. For example, many defibrillators are of the automatic or semi-automatic variety in which the defibrillator determines whether defibrillation is indicated based on the condition of the patient. Automatic or semi-automatic defibrillators normally include a medical monitor for obtaining the patient's electrocardiogram ("ECG") for use in determining whether defibrillation is indicated. These defibrillators often include a strip chart recorder for allowing the emergency medical technicians to view the patient's ECG and to provide a permanent record of the ECG as well as the time of occurrence of pertinent events, such as the time that a defibrillation pulse is generated.
Modem automatic or semi-automatic defibrillators having the above described capabilities contain a great deal of complex circuitry that can become temporarily or permanently inoperative if exposed to such environmental hazards as water or mechanical shock. Similarly, such defibrillators often use relatively fragile and difficult to protect components such as strip chart recorders or display screens. It is therefore important for both economic and safety reasons to ensure that such defibrillators are not damaged by environmental hazards. However, despite the importance of doing so, defibrillators are often damaged by environmental hazards primarily because their physical packaging is not designed to protect the defibrillators, particularly in view of the circumstances under which they are used and the type of individual using them.
Approximately 500,000 heart attacks occur each year outside the hospital, many at home. In the process of rescue defibrillators are inherently exposed to a variety of environmental hazards such as rain, snow, mud, mechanical shocks and vibration. When the emergency medical technician reaches the scene of a heart attack, he or she must act quickly to save the victim, and the emergency medical technician is understandably devoting his or her attention to the victim rather than to safeguarding the defibrillator. Under these circumstances, the defibrillator may be damaged by environmental hazards. For example, after speeding to the scene of a heart attack and then running to the heart attack victim, the emergency medical technician may drop the defibrillator into a puddle of water while devoting his or her attention to quickly attaching defibrillation electrodes to the chest of the victim. The defibrillator will thus be exposed to both water and shock. If this water or shock disables the defibrillator, the victim could die and, in any case, the defibrillator would require expensive repair.
As mentioned above, portable defibrillators traditionally have been used by trained emergency medical technicians since training has been considered necessary to properly diagnose conditions requiring defibrillation. With the advent of automatic and semi-automatic defibrillators, even untrained individuals can successfully defibrillate heart attack victims. As a result, portable defibrillators are now being supplied to a wide variety of relatively untrained individuals, such as police officers, security guards, office personnel, and athletic coaches. While attempts can be made to train emergency medical technicians to safeguard portable defibrillators in emergency conditions, such training does not seem likely to be successful in educating these less trained individuals to adequately protect portable defibrillators from environmental hazards. For these reasons, it seems likely that ever increasing numbers of portable defibrillators and other medical electronic instruments will continue to be exposed to environmental hazards.
In the past, there have been two approaches to packaging portable medical electronic instruments, such as defibrillators. One approach has been to package such instruments in essentially the same manner as hospital based medical electronic instruments, i.e., to not significantly protect such instruments from the environment. Often the only accommodations to making such instruments portable have been attempts to make then relatively small and lightweight, and to provide them with a handle. Needless to say, such instruments are prone to damage when they are exposed to environmental hazards under emergency conditions.
Another approach to packaging portable electronic instruments has been to entirely shield them from the external environment, such as by packaging them in a closed weatherproof container. While this approach may be satisfactory for some types of electronic instruments, it is not acceptable for medical electronic instruments which must be operated and viewed during use. For example, individuals should be able to view the patient's ECG on a strip chart record prior to and after defibrillation. Yet it is not possible to do so if the strip chart recorder is buried deep in an enclosed weatherproof container. On the other hand, strip chart recorders inherently have external openings (since the strip chart paper must be fed out through openings), thus making it impossible for the strip chart to be protected from the environment. Similar constraints exist for other components, such as keyboards, displays, connectors, etc.